Aminoesterenamide Achieved by Three‐Component Reaction Heading toward Tailoring Covalent Adaptable Network with Great Freedom

Abstract

Covalent adaptable networks (CANs) have recently received extensive interests due to their reprocessability and repairability. Rethinking the libraries of the published CANs, most of them are fabricated by one/two-component reactions and few cases utilize multi-component reactions to construct CANs while multi-component reactions are conductive to tailoring the properties of polymers due to their structural designability and flexible choice of raw materials. A novel kind of dynamic covalent bond named aminoesterenamide is presented through three-component reaction between acetoacetyl, amine and isocyanate. Aminoesterenamide exhibits thermal reversibility through dissociating into vinylogous urethane and isocyanate. When it is used to prepare CANs, the synthesized polymer networks can be reprocessed many times via the exchange reaction between aminoesterenamides. Moreover, the forming of aminoesterenamide involving three starting components imparts CANs with great freedom to tailor their properties. Therefore, the authors believe this method that utilizes three-component reaction to fabricate CANs would bring new stories and perspectives to the exploration of new types of CANs.

Chemical Recycling of Step-Growth Polymers Guided by Le Chatelier’s Principle

“…However, this stability poses challenges for the chemical recycling or upcycling of polyureas at the end of their lifespan. Efforts to achieve the recycling of polyureas have focused on introducing dynamic covalent bonds, such as hindered urea, − acylsemicarbazide, , acetoacetyl formed amides, , or pyrazole-urea groups, or incorporating catalysts . These approaches aim to render polyureas recyclable, reprocessable, or healable.…”

Photocurable acylhydrazone covalent adaptable networks with fast dynamic exchange and tunable viscoelastic properties

“…6–13 These crosslinked materials can be reprocessed by inducing network topology changes, providing CANs with the merits of both thermoplastics and thermosets. Currently, various types of dynamic covalent bonds have been successfully incorporated into CANs including esters, 14–17 disulfides, 18–21 vinylogous urethanes, 22–27 acetals 28–31 and imines. 32–35 Among them, imines or Schiff bases have attractive dynamic covalent bonds for the preparation of CANs due to the wide range of biobased aldehydes and ketones, and often catalyst-free reactions with low activation energies.…”

Reprocessable Polyurethane Foams Using Acetoacetyl-Formed Amides

“…In 2021, they further investigated a multiple-component reaction taking place between acetoacetate, isocyanate, and amines, leading at elevated temperatures to an adduct that produces a vinylogous urethane and an isocyanate as an intermediate. , …”

“…59 In 2021, they further investigated a multiple-component reaction taking place between acetoacetate, isocyanate, and amines, leading at elevated temperatures to an adduct that produces a vinylogous urethane and an isocyanate as an intermediate. 60,61 Producing stable and high-performance PUFs is based on optimized industrial processes that can be influenced by a multitude of reaction parameters including catalysis, stabilizers, additives, and blowing agents. In other words, the incorporation of a new type of dynamic bond into such foams can be a highly challenging task.…”